Bob,
This is an excerpt on the L/89 head bolt & washer topic:
Re: Head bolts - L/89 equipped big blocks for 1969
Steve-----
GM parts has everything that you need and under the original part numbers:
1) long head bolts------GM #3877669
2) long head bolts------GM #3877668
3) washers--------------GM #3899696
These exact same washers were used for all 67-71 big blocks with aluminum heads. Chevrolet big block aluminum heads bolt seats were cut deeper by the thickness of the washers so that stock big block head bolts would still engage the same thread depth in the block.
The above-referenced head bolts are the original part numbers and conform to the original specs. However, the headmarkings on currently available bolts are slightly different than originals. On the originals, the ends of the "cross" on the bolt head extended all the way to the head perimeter. The "cross" ends on the current bolts are shorter.
Hope this helps Bob.
Steve